Brake pedal to the floor - Berlingo B9

[classexa]

Hi there. New to the forum

Hopefully you can share some insight because I'm a bit frustrated. The brake pedal is hard like it should be when the car is off but when I start the car it sinks to the floor and I'm not able to pump it up because it sinks right back down. This started after I changed the rear brakes(discs and pads). Have also changed the front brakes after this. I thought the master cylinder was at fault so I replaced it. Still have the same issue. When I look at the pistons at the rear brakes, they go out a bit but is retracting all the way in when i release the brake pedal. They It can't keep up the pressure since the pedal is sinking. There's a quite a gap between the pads and pistons at the rear(5-6mm) but maybe that's normal. Could it be something with the servo or vakuum pump? I don't really know how it all works.

Regards Nick

Berlingo B9 2010 1.6

[Gibbo2286]

This might be what you need, it's a yank but the procedure is the same for the Franch stuff.

[PaulC5]

You might have a lot of air in the brakes that needs bleeding out. To get it out of the abs system though needs a diagnostic and not just pedal pumping. The handbrake should only be adjusted once the rear pistons have been pushed out by pedal pumping and there ought to be a bit of a gap between the caliper cable lever and its stop with the handbrake off so the cable is slightly slack - if not the rear caliper adjusters will not work.

[classexa]

Ok, but it was acting the same way before I replaced the master cylinder. I only replaced discs and pads first. Didn't touch the brake lines. Everything worked fine before I replaced the rear brakes. So it shouldn't have anything to do with bleeding. But of course, I can try bleeding the ABS unit. It's just very strange

[PaulC5]

I am not familiar with the rear calipers on your car- do the pistons wind in or just push in when fitting new pads ? Were they a bit seized/rusty ?

[classexa]

You wind them in. They were very easy to wind back in

When there's air in the system, usually the pedal stops at one point and the pedal is spongy. At least that's how it's been for me in the past. For me it just goes straight down to the floor now

[PaulC5]

When pushing in pistons I usually open the bleed screw to let the fluid out rather than be pushed back in case of air/dirt or reversing the master cylinder seals. But with the new master cylinder that should have overcome that. When that has been replaced though air will have got into the abs. I would disconnect the handbrake cables at the rear calipers and pump the pedal a lot to see if it pushes the pistons out and they stay out.

On our C5 I replaced a front caliper and ended up having a dealer bleed the brakes with a diagnostic since no matter what I tried I could not get a good pedal.

[classexa]

When I pull the parking brake now, the piston goes out a bit, but it's nowhere near the pads. So it doesn't take.

When I brake, the front takes. Maybe because there's no space in between there. In the rear the piston doesn't come close to the pad. Should the piston stay out after pumping it or should it retract all the way in like it does now? Feels like there's too much space between piston and pad in the rear

Is it possible to screw the pistons out a bit and see if that helps?

[Gibbo2286]

Just a thought, have you got the correct pads in the rear? there's usually very little space when new pads are fitted.

[classexa]

The pads should be correct. They're ordered on OE number(16 682 475 80). They're 16,6mm thick which it should be I think. Here's a picture

[PaulC5]

Even if the pads were wrong, they are a lot thicker than the old so would not explain the pistons not pushing out. Your idea of screwing the pistons out might help, it is possible the internal auto adjuster has been affected when they were screwed in.

[classexa]

Yeah, I'll try that tomorrow. I'll report back

[classexa]

So I screwed the pistons back out so there were no space between the pads and pistons. Sure, the brakes engages and pistons stay there but the pedal is still sinking. I tried to bleed the ABS unit but the pump only engaged on the right side. But there were hardly any air coming out. Don't know what to do next.

[Paul-R]

Did you use a high-end code reader (preferably Diagbox) and go through a special procedure for brake bleeding? There might not be one for a Berlingo but most ABS equipped cars do.

[classexa]

I used a TOPDON diag tool. It had a procedure for brake bleeding which I followed